The mission of Neighborhood House (NH) is to help diverse communities of people with limited resources attain their goals for self-sufficiency, financial independence, health and community building. In this framework, NH seeks to impact the low income, immigrant and refugee communities in and around public housing by reducing health disparities by providing health education, access to health related services, and opportunities to participate in healthy lifestyles. These activities are pursued in a responsive, culturally competent manner that reflects community participation principles. The Partnership for Fitness and Healthy Living in Marginalized Communities will fulfill this mission by 1) improving the health of residents of pubic housing through increased physical activity; 2) providing community building through the community participatory research framework. The majority of U.S. adults fail to obtain adequate physical activity, despite the numerous health benefits associated with being more active, including reduced cardiovascular disease, diabetes, obesity, and some cancers. Low physical activity and higher risk for these long-term health problems exist within low income and ethnic minority populations. The present project employs a comprehensive community-based participatory research (CBPR) approach to working with public housing communities in south King County (Seattle area) with the primary aim to increase residents' physical activity and thus improve health. Based on prior partnerships and promising preliminary findings from a community walking program stemming from other CBPR work, this project engages a collaboration of community residents, community service organizations, public health professionals, and researchers to develop and evaluate the process, implementation, and impact of physical activity intervention in two public housing communities. It is hypothesized that building social capital and modifying built environment (e.g., through advocacy) will support and sustain the physical activity interventions. Process and intervention implementation evaluation will involve qualitative assessment strategies such as focus groups and interviews. In addition to these, intervention impact evaluation involves baseline and follow-up start-of-the-art quantitative assessment of physical activity, health status, social capital, and perceived built environment.